Modelling of Folding Wing-Tip Devices for Gust Loads Alleviation

Cheung, Ronald C.; Wales, Christopher J A; Rezgui, Djamel; Cooper, Jonathan E.; Wilson, Thomas

doi:10.2514/6.2018-0462

Cited by 4 publications

(4 citation statements)

References 11 publications

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“…A previous study 3 investigating non-zero-value hinge angle configurations and variation in the folding hinge stiffness demonstrated that the peak wing root bending moment could be reduced by allowing the wing-tip to fold during gust encounters. This finding agrees with several other studies [4][5][6] that also utilized simple passive means for controlling the folding motion. All these studies found that low hinge stiffness in their respective passive system gave a good level of gust load alleviation performance, however further gains could be obtained if the responsiveness of the folding action could be improved.…”

Section: Introductionsupporting

confidence: 93%

Testing of Folding Wing-Tip for Gust Load Alleviation in High Aspect Ratio Wing

Cheung¹,

Rezgui²,

Cooper³

et al. 2019

AIAA Scitech 2019 Forum

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Folding wing-tips have begun to feature on recent aircraft designs, as a solution for compliance with existing airport gate width, whilst the higher aspect ratio will lead to lower induced drag and better overall fuel efficiency. Recent studies have suggested that by allowing folding of the wing-tip during flight, additional gust load alleviation can be achieved. This paper describes the follow-on work from a previous experimental study, in which the folding wing-tip concept is now applied to a new wind tunnel model of a high aspect ratio wing with a much-reduced bending stiffness. Using a low-speed wind tunnel with a vertical gust generator, the experiment examined the load alleviation performance through a range of one-minus-cosine gust inputs and found up to 11% reduction in peak wing-root bending moment. In addition, a movable secondary aerodynamic surface was fitted to the folding wing-tip which demonstrated that such a device was able to control the orientation of the folding wing-tip effectively in steady aerodynamic conditions, as well as achieving further reduction in peak wing-root bending moment during gust encounters through active control.

show abstract

Section: Introductionsupporting

confidence: 93%

Testing of Folding Wing-Tip for Gust Load Alleviation in High Aspect Ratio Wing

Cheung¹,

Rezgui²,

Cooper³

et al. 2019

AIAA Scitech 2019 Forum

Self Cite

View full text Add to dashboard Cite

show abstract

“…A previous study by the authors 2 investigating non-zero-value hinge angle configurations and variation in the folding hinge stiffness demonstrated that the peak wing root bending moment could be reduced by allowing the wingtip to fold during gust encounters. This finding agrees with several other studies [3][4][5] that showed that a lower folding hinge stiffness tended to improve the gust load alleviation performance.…”

Section: Introductionsupporting

confidence: 93%

Analyzing the Dynamic Behavior of a High Aspect Ratio Wing Incorporating a Folding Wingtip

Cheung¹,

Rezgui²,

Cooper³

et al. 2020

AIAA Scitech 2020 Forum

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High aspect ratio wings have been the focus of recent aircraft designs for improving fuel efficiency through induced drag reduction. The lengthened wingspan derived from these designs have led to the introduction of folding wingtips in order to meet airport gate width requirements. Previous numerical and experimental studies have demonstrated that folding wingtips can also provide a gust load alleviation benefit, when the folding wingtips are able to rotate freely about the hinge during the gust encounter. This work examines the dynamic characteristics and behavior of the folding wingtip, and the overall wing in such a configuration. A series of wind tunnel tests was conducted using a specially designed high aspect ratio wing model to establish its modal characteristics through application of a steppedsine frequency sweep, performed using a gust generator as well as a secondary aerodynamic surface incorporated into the wingtip as the excitation source. In addition, a pseudo-random gust sequence was used as a faster test method through broadband excitation, which yielded results that were in excellent agreement with the stepped-sine methods. Nomenclature Symbols α = Angle of attack γ = Hinge angle θ = Fold angle of the wingtip f = Frequency v = Wind tunnel velocity

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“…It was found that a low hinge stiffness gave a good level of gust load alleviation performance, with results suggesting further gains could be obtained if the responsiveness of the folding action could be improved. Several other studies [16][17][18] that also utilized simple passive means for controlling the folding motion all concluded with similar findings regarding the requirement of low hinge stiffness as well. More complex solutions have been proposed to address this issue, including the use of nonlinear spring systems [19,20] and bi-stable constructs [21] to provide the required hinge stiffness properties.…”

Section: Introductionsupporting

confidence: 65%

“…and ̂ is a unit vector in the direction of the folding hinge axis, which is ̂= { cos −sin 0 } (18) The local angle of attack of the wingtip is related to the velocity vector through tan = 3 1 = sin cos − cos sin sin cos cos + sin sin sin + cos cos 2 (1 − cos ) (19) which yields = arctan ( tan cos − sin sin 1 + tan sin sin + sin 2 (cos − 1) )…”

Section: Acknowledgmentsmentioning

confidence: 99%

Testing of Folding Wingtip for Gust Load Alleviation of Flexible High-Aspect-Ratio Wing

Cheung

Rezgui

Cooper

et al. 2020

Journal of Aircraft

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Folding wingtips have begun to feature on recent aircraft designs, as a solution for compliance with existing airport gate width regulations whilst enabling high aspect ratio wings for lower induced drag and better overall fuel efficiency. Recent studies have suggested that by allowing folding of the wingtip during flight, additional gust load alleviation can be achieved. This paper describes the first experimental study of the folding wingtip concept, when applied to a highly flexible, high aspect ratio wing. Using a low-speed wind tunnel with a vertical gust generator, the experiment examined the load alleviation performance through a range of oneminus-cosine gust inputs and found up to 11% reduction in peak wing-root bending moment. In addition, a movable secondary aerodynamic surface was fitted to the folding wingtip which demonstrated that such a device was able to control the orientation of the folding wingtip effectively in steady aerodynamic conditions, as well as achieving further reduction in peak wing-root bending moment during gust encounters through active control.

show abstract

Modelling of Folding Wing-Tip Devices for Gust Loads Alleviation

Cited by 4 publications

References 11 publications

Testing of Folding Wing-Tip for Gust Load Alleviation in High Aspect Ratio Wing

Testing of Folding Wing-Tip for Gust Load Alleviation in High Aspect Ratio Wing

Analyzing the Dynamic Behavior of a High Aspect Ratio Wing Incorporating a Folding Wingtip

Testing of Folding Wingtip for Gust Load Alleviation of Flexible High-Aspect-Ratio Wing

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